Shaman Rattles

I made my first rattle with a piece of rawhide left over from making
my first moose drum. What an adventure it was, because I had no guide, just a casual
reference from my first drum teacher.
I have learned a lot since then. I try several fillings with every rattle I make.

Will it sound best with corn, beads, or quartz crystals?
What does the rattle want for its completion -- possibly ant hill stones from
the Posi ruins in New Mexico, or possibly stones or seeds from my client?